What can cause deficiency of calcium?

January 6, 2026 •

4 min read

According to the National Institutes of Health, vitamin D deficiency is a significant and common cause of low blood calcium levels, as vitamin D is essential for the body's absorption of this mineral. Low levels of calcium can also stem from a variety of other factors, including underlying medical conditions and certain medications.

Quick Summary

Several factors can lead to hypocalcemia, including inadequate dietary intake, insufficient vitamin D levels, and medical conditions like kidney disease and hypoparathyroidism. Certain medications and lifestyle choices can also interfere with calcium absorption and metabolism. Understanding these causes is key to prevention and management.

Key Points

Vitamin D is Essential: A deficiency in vitamin D is a primary cause of low calcium, as it is necessary for intestinal calcium absorption.
Kidney Disease is a Major Factor: Chronic kidney disease impairs the activation of vitamin D, leading to poor calcium regulation and potential deficiency.
Hormonal Imbalances Play a Role: Hypoparathyroidism, a rare condition with insufficient parathyroid hormone, directly leads to low blood calcium levels.
Dietary Intake is Foundational: Poor consumption of calcium-rich foods or a diet high in absorption-inhibiting substances like phytates and oxalates can cause a deficit.
Certain Medications Affect Absorption: Drugs such as long-term corticosteroids, proton pump inhibitors, and diuretics can interfere with calcium metabolism and lead to deficiency.
Underlying Malabsorption is a Cause: Conditions like inflammatory bowel disease or celiac disease can prevent the body from effectively absorbing calcium from food.

Understanding the Core Functions of Calcium

Calcium is the most abundant mineral in the human body, with 99% stored in the bones and teeth. This mineral is crucial for more than just skeletal health; it plays a vital role in muscle function, nerve transmission, and blood clotting. The body tightly regulates blood calcium levels within a very narrow range, and any significant drop is a condition known as hypocalcemia, or calcium deficiency. The causes of this imbalance are complex and can be linked to poor dietary intake, metabolic issues, hormonal disorders, and even specific medications.

Dietary and Lifestyle Factors

For many, the most straightforward cause of calcium deficiency is simply not consuming enough of it. However, the issue can be more nuanced and tied to how the body absorbs and processes the calcium that is consumed.

Inadequate Dietary Intake

Low Consumption: A diet lacking in calcium-rich foods like dairy products, leafy greens, fortified cereals, and canned fish can directly lead to a deficiency.
Dietary Restrictions: People with lactose intolerance, dairy allergies, or those following a vegan diet may struggle to meet their daily calcium requirements if they do not supplement properly.
Absorption Inhibitors: Some foods contain compounds called oxalates and phytates, which bind to calcium and reduce its absorption. Examples include spinach (high in oxalate) and whole grains (high in phytates).

Vitamin D Deficiency

Vitamin D is a fat-soluble vitamin that is essential for calcium absorption in the intestines. Without sufficient vitamin D, the body cannot effectively absorb the calcium from the food you eat. Causes of vitamin D deficiency include:

Limited Sun Exposure: The body naturally produces vitamin D when exposed to sunlight, so those who spend little time outdoors are at risk.
Dietary Lack: Insufficient intake of vitamin D-rich foods like fatty fish, egg yolks, and fortified products also contributes to low levels.
Darker Skin: Individuals with more melanin in their skin produce less vitamin D from sun exposure.

Medical Conditions Affecting Calcium Levels

Beyond simple dietary factors, a number of medical conditions can disrupt the body's delicate calcium balance.

Hypoparathyroidism

This rare condition occurs when the parathyroid glands, four small glands in the neck, don't produce enough parathyroid hormone (PTH). PTH is critical for regulating calcium and phosphorus levels in the blood. Too little PTH results in low blood calcium and high blood phosphate. It can be caused by surgery (especially thyroid surgery), autoimmune disorders, or genetic factors.

Kidney Disease

Chronic kidney disease (CKD) can severely impact calcium levels. Healthy kidneys are responsible for activating vitamin D, which is necessary for calcium absorption. As kidney function declines, the production of active vitamin D decreases. Moreover, failing kidneys may not be able to excrete excess phosphorus, which can bind with blood calcium and further lower its concentration.

Gastrointestinal Issues

Conditions that cause malabsorption can prevent the intestines from properly absorbing calcium from food. These include:

Inflammatory Bowel Disease (IBD)
Celiac Disease
Pancreatitis, which can cause fats to bind with calcium
Bariatric Surgery

Hormonal Changes

Menopause: Postmenopausal women are at a higher risk of calcium deficiency because the decrease in estrogen production reduces calcium absorption and increases bone loss.

Medications and Their Impact on Calcium

Certain drugs can interfere with calcium metabolism, leading to hypocalcemia. It is important to discuss potential side effects with a doctor if you are taking any of the following:

Corticosteroids: Long-term use of steroids can decrease calcium absorption from the gut and increase its excretion via the kidneys.
Proton Pump Inhibitors (PPIs): These drugs, used to treat acid reflux, can reduce stomach acid, which is necessary for the absorption of some forms of calcium.
Loop Diuretics: These medications increase the excretion of calcium in the urine.
Anticonvulsants: Certain anti-seizure medications, such as phenytoin and phenobarbital, can increase the metabolism of vitamin D, leading to reduced calcium absorption.
Bisphosphonates: While used to treat osteoporosis, certain types can cause a severe but temporary drop in blood calcium, especially in vitamin D-deficient individuals.

Comparison of Key Causes of Calcium Deficiency


Cause	Mechanism	Primary Impact	Associated Risks
Inadequate Diet	Low intake or poor absorption due to dietary choices or inhibitors like phytates and oxalates.	Reduced calcium intake from food.	Osteoporosis, bone weakness, rickets in children.
Vitamin D Deficiency	Insufficient vitamin D limits intestinal calcium absorption.	Decreased intestinal absorption of calcium.	Osteomalacia (soft bones), muscle weakness, osteoporosis.
Chronic Kidney Disease	Kidneys fail to activate vitamin D and balance minerals like phosphorus.	Impaired vitamin D activation and mineral imbalance.	Renal osteodystrophy, faster progression to kidney failure.
Hypoparathyroidism	Underactive parathyroid glands produce insufficient parathyroid hormone (PTH).	Low blood calcium and high blood phosphate levels.	Muscle cramps, tetany, seizures in severe cases.
Medications (e.g., PPIs, Diuretics)	Interference with calcium absorption, metabolism, or increased excretion.	Reduced usable calcium in the body.	Hip fractures, other fractures with long-term use.
Malabsorption Disorders (e.g., IBD)	Intestinal damage prevents proper nutrient absorption.	Decreased calcium absorption from the digestive tract.	Poor nutritional status, bone disease.

Conclusion

Identifying what can cause deficiency of calcium is a critical step toward managing and preventing its health consequences. While dietary insufficiency is a prominent factor, the issue is often multifaceted and involves a combination of nutritional, hormonal, and medical factors. Conditions like kidney disease, hypoparathyroidism, and malabsorption disorders can disrupt calcium regulation in profound ways. Furthermore, common medications and natural life stages like menopause can also significantly impact calcium status. Addressing calcium deficiency requires a comprehensive approach, including a proper diagnosis by a healthcare provider to pinpoint the root cause, which may involve dietary changes, supplements, or treating an underlying condition. For further information on dietary guidelines, consult the Bone Health & Osteoporosis Foundation.

Frequently Asked Questions

While inadequate dietary intake is a major contributor, vitamin D deficiency is arguably the most common and critical cause, as it impairs the body's ability to absorb calcium from food.

Chronic kidney disease can lead to calcium deficiency because the kidneys are responsible for converting vitamin D to its active form. Without enough active vitamin D, the body cannot absorb enough calcium.

Yes, several medications can interfere with calcium absorption or increase its excretion, including long-term use of corticosteroids, diuretics, certain anti-seizure drugs, and proton pump inhibitors (PPIs).

Hypoparathyroidism is a condition where the parathyroid glands produce too little parathyroid hormone (PTH), which is crucial for regulating calcium levels. This leads to abnormally low blood calcium and high phosphate levels.

A vegan diet can increase the risk of calcium deficiency if not managed properly. While many plant-based foods contain calcium, some also contain compounds like oxalates and phytates that inhibit absorption. Proper planning and potentially supplementation are necessary.

Yes, conditions like celiac disease and inflammatory bowel disease (IBD) can damage the intestinal lining, impairing its ability to absorb calcium and other nutrients, leading to a deficiency.

Hormonal changes, especially the decrease in estrogen after menopause, can significantly increase a woman's risk of calcium deficiency and associated bone loss (osteoporosis).